An intensely loud ringing sound emanates from the space between the two constructs.

DC15 CON Saves:
Thing #1: CON Save: 9
Thing #2: CON Save: 10

 Their featureless ball heads suddenly exhibit a spiderweb of small cracks. They pause for a moment, then charge.
Kei rushes around the pit and past Dwal, well up the hallway.

The constructs lumber forward and stop in front of Peri. Side-by-side, they fill the hallway and prepare to smash in parallel.

Peri:

"Well that certainly got their attention!" He jabs his spear downward at the one to the west, hoping it does more damage to the creature than it does to his spear. He drops onto the thing's shoulder and attempts to kick its head into the wall, using the force of that kick to propel a kick into the other thing's head, before springing to the wall and climbing back onto the ceiling and away to the north, past his friends.
Spear:   27 for 7 magical piercing to Thing 1
FoB #1: 8 for 6 bludgeoning to Thing 1
FoB #2: 21 for 8 bludgeoning to Thing 2

((Drunken technique to Disengage, then move up by Kei, still hanging upside down.))

Gerrard:

Holding his position, Gerrard readies to receive the charge of the iron guards if they come within his reach.

Readied Attack:

Boko, now that everyone is out of the way, picks up the ladder and pretends to turn around to keep running, attempting to keep up the charade.

Dwal will move up to the edge of the pit, watching the creatures as they advance. Once they get within 15 ft. Dwal will cast Lightning Lure.
The Strength DC is 13 and if the target fails it will pull it 10 ft. towards Dwal. Dwal is attempting to pull the construct into the acid pit. 

"If this works" Dwal says. "we'll still have ta beat it down a bit before it falls.

Peri manages to loosen its ball head with his spear before smashing it into the stone wall. It instantly rights itself, but it seems to be somewhat unbalanced now. Peri vanishes across the ceiling to the north side of the pit.

Gerrard readies for the next charge as Boko lifts the ladder. Dwal slips in front of Boko and casts his spell.

Thing #1 DC 13 Strength check: 19

These constructs are clearly ponderously heavy; Dwal's arcane lure nearly draws it onto the trap doors, but in the end, the thing was just too heavy for his spell to pull.

The constructs advance, their weapons ready to smash.

(Constructs' intelligence checks re: trap doors: 0 and -1)

Both constructs lumber forward without any regard whatsoever for the trap doors. 

The doors fall open; both of your pursuers fall in. The pit is 10 feet deep, with long wooden spikes affixed to the bottom.
Thing #1 takes 1 bludgeoning damage from the fall and 7 piercing damage from the spikes.
Thing #2 takes 4 bludgeoning damage from the fall and 7 piercing damage from the spikes.

DC 10 Strength (Athletics) checks to climb out:
#1 Strength check: 20
#2 Strength check: 4

Both successfully climb up the other side, shoving everyone a few feet backward.
In the process, Thing #2 gets a taste of Gerrard's rapier.

They are both on the lip of the north side of the pit. Both are showing some wear, and yet still have a lot of fight left in them.

Everyone may act.

Peri:

Peri whoops with triumph as the statues plummet to their doom in the pit of... Wait, they're climbing out already? He edges forward and sees this pit lacks the acid of the other pit they'd found. Disappointed, he blasts another bolt of energy at the more beat-up of the pair.
EB #1: 19 for 4
EB #2: 19 for 8

He ducks around the corner (2 squares east) just in case these things explode when they die.

((Ooh, Crit damage for the 2nd beam! 3))

Being up front Dwal will arm himself with his battle axe and take a swing.

Hit: 18

Damage if hits: 8

"Figures they'd climb out that fast." he says. 

Gerrard:

Trying to hold his ground at the leading edge of the pit, Gerrard realizes that it was not nearly as deep as he hoped, and as he steps back to keep from being grabbed and used as a handhold on the way out of the pit, the strange metal creature takes advantage and stands up precariously on the edge of the pit.

With his companions attacking at hopefully pushing at least one back into the pit, Gerrard focuses on whichever remains, saying in somewhat of a surprised voice, “Wow, that kind of actually worked,” as he launches into a full attack routine.

Rapier:  Attack: 17 Damage: 9

Rapier:  Attack: 20 Damage: 9

Main Gauche:  Attack: 9 Damage: 10

Boko reaches out just past Dwal and Gerrard, offering to swap places with Dwal if he wishes, but either way she casts thunderwave starting right at the iron men for 10 thunder and pushback on a failed CON 15 save.

Gerrard begins to lay his rapier into #2, finding he can actually to a fair amount of damage to the thing's arcane coating. It's beginning to look fairly beat up.

Peri fires a pair of crackling beams into the same construct, melting a large oblong gash on its smooth, spherical head. He ducks around the corner out of their sight.

Dwal takes a swing at the other one, but his axe doesn't land well on its tough exterior, and it shears off doing no damage.

Kei fires an [Tooltip Not Found] through Gerrard's legs: Spell attack vs. #2: 18  Hit: 10 force damage.

Boko slips into the front line and releases a wave of thunderous force at both.
#1 DC15 CON Save: 16
#2 DC15 CON Save: 19  

...

Construct #2 (the one nearest Gerrard) falls into the pit, taking 2 additional damage from the fall. It attempts to climb out again: DC10 Strength check: 12

With a low, whirring sound, Construct #1 begins to spin at its waist, whirling with its hammer and blade extended.

Gerrard, Dwal, and Boko must each make a DC 13 Dexterity saving throw, or take 16 bludgeoning damage on a failed save, or half as much damage on a success. Kei and Peri are out of reach of its extended, whirling weapons.

 #2 tries, but fails, to climb out of the pit, its sides slippery with moss and slime.

Everyone may act (following some Dex saves!)

Dwal's Dex save: 2

Dwal's Concentration save to maintain Bless: 14

Gerrard:

Gerrard desperately tries to avoid the flailing blades, dodging and partying the multitude of attacks as best he can.

Dexterity Save:  10 plus bless 2

Parry:  6

Boko dex save: 26

She then casts thunderwave again, in the same manner, hoping to push the dangerous thing back and to hit the one in the pit too. 9 thunder damage on a failed CON 15 save

Gerrard:

Shuddering from the massive attack, Gerrard responds with a few slices of his own, then tries to Shove the construct back into the pit!

Rapier attack 1  Attack: 26 Damage: Unable to parse dice roll. plus Bless:  1

Rapier Attack 2:  Attack: 18 Damage: Unable to parse dice roll. plus Bless:  4

Shove in place of Main Gauche Attack (Athletics):  15 plus Bless:  1

Gerrard attempts to push Construct #1 back into the pit, but finds it simply too massive to budge. His blades, likewise, fail to find purchase on the arcane automaton.

Boko leaps straight up, kicking off the wall over Dwal's head, dodging most (but not all) of the spinning weapons, before unleashing a second wave of thunderous force on the constructs, together with a second deafening boom that rolls through the underground complex.

Construct #1 DC15 Con Save: 5
Construct #2 DC15 Con Save: 13

...and succeeds where Gerrard failed, knocking the first construct into the pit to join its partner. It takes another 4 bludgeoning damage from the fall.

Peri, Dwal, and Kei may act.

Kei 

An idea springs to mind as he watches the second construct fall into the pit. Pushing past the others he reaches deep into his robe. Just as he reaches the lip of the pit he withdraws a square grey coloured patch. He throws it at the mouth of the pit. As it passes the edge of the pit the patch expands to fill the opening with a huge steel door. It clanks into place and a large bar slides across its face anchoring the door closed - horizontally across the pit. "Tada! Brand new trapdoor." he turns and bows to the group, quite proud of his actions.